A duty-bound family woman, unbearably taunted by her cruel husband and co-conspiring offspring, finds release in the joy of serial killing, until seduced by an unsuspecting victim.

The "falling for one of her victims" is B story fuel.

Example:
“A bullied mother of a toxic household becomes a vindictive serial killer of family look-alikes”

Hope you find this constructive, keep going!

"duty-bound family woman"=protagonist

"taunted by her cruel husband"=inciting incident

"joy of serial killing"=goal

"seduced by an unsuspecting victim"= 2nd inciting incident

Great to see exploration of feminine character - particularly casting a female as serial killer breaks with many stereotypes.

Protagonist's character flaw is being duty-bound to a cruel husband. If this were my logline, I'd reflect on how appealing this might be for audiences. If these events were cast back in history, to more gender role conservative times, then maybe a woman might tolerate a bad husband. But even Henrik Ibsen's 1879 play "A Doll's House" shows female liberation happened a longtime ago. What would motivate a woman to stick around a bad husband, let alone transform her into a serial killer?

Take the story of "The Postman Always Rings Twice (1981)". Here money and love motivate murder - of only one victim. Consider reducing this logline down to one inciting incident, and expanding upon more likeable characterization of the protagonist.

The Dexter TV series does it well, breaking with convention, by making a serial killer likeable, yet motivated. Breaking out the Silence of the Lamb mold.

I also find this intriguing, particularly because it is a female lead involved in possible justified deviant behavior.

I would omit a few words from this simply because I feel you may be repeating things, that would then give you more room to add new details if you wished.

For example "family" is implied when you mention the husband and offspring

"unbearably" possibly remove that and increase the stakes of the word taunted with a stronger word choice?.

Also "release in the joy" could we not argue any emotion is a release, e/motion = energy in motion could you possibly omit one of those words or rephrase with a stronger word choice.

"emancipates herself in ....."

A question, what kid of serial killing is it? Could it be possible to add a little specificity with regards to that?